solution for Ex. 1 https://github.com/ivanStraltsou/code-wars/tree/master/katas/regexp

regexp.clone.js

RegExp.clone = function (regExp) {
    var pattern = regExp.source,
        isGlobal = regExp.global,
        isIgnoreCase = regExp.ignoreCase,
        isMultiline = regExp.multiline;
        flags = '';

    flags += isGlobal ? 'g' : '';
    flags += isIgnoreCase ? 'i' : '';
    flags += isMultiline ? 'm' : '';

    return new RegExp(pattern, flags);
};

RegExp.prototype.clone = function () {
    return RegExp.clone(this);
};

// Example:
/*
 *  var regex = /^[abc]/gim,
 *      cloneRegex1 = regex.clone(),
 *      cloneRegex2 = RegExp.clone(regex);
 *
 *
 *  regex.exec("ZZ\nZZCZ\nCZZ\na");       // => ["C"]
 *  cloneRegex1.exec("ZZ\nZZCZ\nCZZ\na"); // => ["C"]
 *  cloneRegex2.exec("ZZ\nZZCZ\nCZZ\na"); // => ["C"]
 *
 *  regex.exec("ZZ\nZZCZ\nCZZ\na");       // => ["a"]
 *  cloneRegex1.exec("ZZ\nZZCZ\nCZZ\na"); // => ["a"]
 *  cloneRegex2.exec("ZZ\nZZCZ\nCZZ\na"); // => ["a"]
 *
 *  regex === regex             // => true
 *  regex === cloneRegex1       // => false
 *  regex === cloneRegex2       // => false
 *  cloneRegex1 === cloneRegex2 // => false
 *
 */

Если нужно сохранить и позицию, то

RegExp.clone = function (regExp) {
    var pattern = regExp.source,
        isGlobal = regExp.global,
        isIgnoreCase = regExp.ignoreCase,
        isMultiline = regExp.multiline;
        flags = '',
        clone;

    flags += isGlobal ? 'g' : '';
    flags += isIgnoreCase ? 'i' : '';
    flags += isMultiline ? 'm' : '';

    clone = new RegExp(pattern, flags);
    clone.lastIndex = regExp.lastIndex;

    return clone;
};

RegExp.prototype.clone = function () {
    return RegExp.clone(this);
};